Method of preparing sodium and potassium hyposulphite



. 1 2,991,152 METHOD OF PREPARING SODIUM AND POTASSIUM HYPOSULPHITE ieter G'oerrig, Lohmar (Siegkreis), Germany (Farbenfabrik'en Bayer A.G., Leverkusen,. Germany), and Friedrich Schubert, Leverkusen, Germany; said Schuberta'ssignor to said Goerrig No Drawing. Filed Jan. 13, 1958, Ser. No. 708,402

Claims priority, application Germany Jan. 16, 1957 .1 '4 Claims. (Cl. 23116) It is known that tree hyposulphurous acid, H S O is very unstable. A salt (C080 been isolated therefrom, but this salt has no practical value. On the other hand, two derivatives thereof are of considerable technical interest.

By combining the hyposulphurous acid with sulphurous acid and forming an alkali salt, sodium dithionite (1921 8 is formed, which is used under the name of hyposulphite" or hydrosulphite as a valuable reducing agent.

Solutions which contain the free hyposulphurous acid or the salts or derivatives thereof, such as Na S O can be reacted with formaldehyde to yield quite a stable compound (oxymethane sulphinic acid) which is also used as its sodium salt, (for example under the name Rongalit as a valuable reducing agent.

In the production of such derivatives of hyposulphurous acid, a distinction should therefore be made between the stepof the reduction of the sulphurous acid or its salts, which yields the free hyposulphurous acid or its salts, and

. the further step which converts the solutions of unstable which can only take place on the surface of the metals and which yields the electrons for the reaction (in the ideal case) Accordingly, such a reaction does not take place suddenly, but requires a long time, and in particular care must be takenthat the dissolution of the metal does not take place more quickly than sulphurous acid or its derivatives can migrate to the metal surface, since otherwise useless evolution of hydrogen is initiated, this causing a loss of the reducing agent.

The present invention is concerned with a process for the production of derivatives of hyposulphurous acid by reduction of sulphur dioxide or its derivatives, the process consisting in that the reduction is carried out with a borohydride.

The process of the invention therefore uses not metals, but solutions inwhich the reducing agent is present as an ion, and in fact as an anion. It is preferred to use a water-soluble salt of hydroboric acid, for example NaBI-I KBH or Ca(BH The solutions thereof react within the sulphurous acid or its salts or other derivatives in a substantially quantitative manner. It has been found that when solutions are mixed by pouring them together in a ratio such as is required by the following equation the reaction in accordance with the foregoing equation is complete after one minute at 20 C.

The examples show in a number of individual cases be varied within very wide limits.

sulphur changing how the reaction can be carried out. The conditions can For example, it is not of decisive importance in the process of the invention whether gaseous or a sulphurous acid ester is introduced into an alcoholic solution containing NaBI-L, and NaOH, or whether solid LiBH is introduced into an aqueous calcium bisulphite solution.

It is a characteristic feature of the invention that 80 or derivatives of S0 which are at the oxidation stage of 80, are reacted with borohydrides, all or some of the into the oxidation stage of hyposnlphur ous acid.

Further working up of the reduced solution, for example the isolation of the M1 8 0, or or the can be carried out if desired, but it is possible for the reduction solution to be used directly.

The invention is further illustrated by the following example without being restricted thereto.

Example 150 l. of a fNaHSO solution containing 81 kg. of NaHSO were introduced into an open tube container and diulted with water up to about 400 l. A solution of 5.28 kg. of KBH in about l. of water are in with stirring in the course of 15 minutes, a slight evolution of gas being observed. The temperature of the combined solution rose to 23 C., while the individual solutions had a temperature of only 8 C. After the solutions were thoroughly mixed, 10 l. of caustic soda solution (32 B.) were added and the total liquid was made up to 600 l.

The solution was used in the dyeing of various vat dyestuffs on the jig in the course of 28 hours, instead of concentrated hydrosulphite.

It was determined that the introduction into the jig.

liquor of 9.25 l. of the solution after 1 hour, 9.10 l. of the solution after 3 hours, 9.10 l. of the solution after 6 hours, 9.05 l. of the solution after 9 hours, 9.25 l. of the solution after 22 hours, 9.30 l. of the solution after 28 "hours,

brought about the same Na S O concentration as the dissolution of 1.00 kg. of hydrosulphite conc. containing 92.7% of Ida- 8 0 in the same jig liquor.

In the temporal mean value of 28 hours, the above solution had a concentration of 100 kg. of pure Na S O /l, i.e. the solution contained 60 kg. of Na S O which led to a chemical yield of the reaction.

of about 90.7% of the theoretical.

The dyeings were carried out with 9.20 l. of the above solution or 0.081 kg. of KBH; 1.24 kg. of NaHSO P ......1 July 4,1951,

3 4 potassium salts of hyposulphurous acid by the reduction dium borohydride in the ratio required in accordance of the corresponding metal bisulphite in aqueous soluwith the equation:

tion, the step which comprises reducing the said bisulphite by means of a borohydride which is a memberv se- Nam-14+ 8NaHSO3 )NaBO2+6H2O+4Na2SO4 lected from the group consisting of sodiumand potas- 5 Refere e Cited in the fil f h Patent sium borohydride. 7 7

3. In a process for the production of sodium hypo- UNITED STATES PATENTS sulphite by the reduction of sodium hydrogen sulphite in 2,204,476 Dorph June 11, 1940 aqueous solution, the step which comprises reducing the 2,461,661 Schlesinger et a1. Feb. 15, 1949 sodium hydrogen sulphite by means of sodium boro- 10 2,744,810 Jackson May 8, 1956 hydride. 1

4. In a process for the production of sodium-hypo- OTHER REFERENCES sulphite by the reduction of sodium hydrogen sulphite in Sodium y Bulletin 507A, Metal Hydlides aqueous solution, the step which comprises vmixing 1 -24 Congress St, Beverly, Mass. Received, dated aqueous solutions of sodium hydrogen sulphite and so- 15 1950. P g 1 and UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,991 152 July 4, 1961 Dieter Goerrig et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification, lines 4 and 5, strike out "(Farbenfabriken Bayer A.G., Leverkusen, Germany)".

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents USCOMM-DC 

1. IN A PROCESS FOR THE PRODUCTION OF SODIUM AND POTASSIUM SALTS OF HYPOSULPHUROUS ACID BY THE REDUCTION OF THE SO2-ION IN AQUEOUS SOLUTION, THE STEP WHICH COMPRISES REDUCING THE SO2-ION BY MEANS OF A BOROHYDRIDE WHICH IS A MEMBER SELECTED FROM THE GROUP CONSISTING OF SODIUM AND POTASSIUM BOROHYDRIDE. 